The present invention relates to a computerized method for generating a finite element model of a pneumatic tire capable of improving simulation accuracy.
In general, a pneumatic tire is manufactured by first building a raw tire by assembling rubber members, cord reinforced layers and the like, and then vulcanizing the raw tire in a mold by pressurizing the inside of the raw tire. Therefore, the cords embedded in the vulcanized tire usually have residual stress. Due to the residual stress, accordingly, there is a tendency such that the shape of the demolded tire becomes smaller than the finished tire shape in the vulcanization mold.
In Japanese Patent Application Publication No. 2010-191612, a computerized method for simulating a rolling tire is disclosed. In this method, a finite element model of the tire is generated, based on the finished shape of a tire in a vulcanization mold, namely, the shape of the mold cavity.
As a result, there is a tendency that the shape of the tire model generated based on the finished tire shape in the vulcanization mold differs from (usually, becomes smaller than) the shape of the tire during use.
Thus, it is difficult to fully improve the accuracy of simulation using such a tire model.
The present inventor, therefore, made researches and found that simulation errors are large when the tire is provided in the tread portion with so called zero-degree band (namely, a cord reinforced rubber layer wherein the cord angle is about 5 degrees or less with respect to the tire circumferential direction). In such a tire, the residual stress becomes relatively large in the band when compared with other cord reinforced layers, and the band has much effect on the tire shape.